1. Field of the Invention
The present invention relates to an apparatus and a method to determine and compensate for a mechanical resonance frequency in a data storage system, and more particularly, to an apparatus and a method for rapidly and precisely determining, adaptively filtering, and compensating for a mechanical resonance frequency in a data storage system.
2. Description of the Related Art
In general, a Hard Disk Drive (HDD) is a data storage system that consists of a Head Disk Assembly (HDA) configured with mechanical components and electrical circuits. A resonance generated by a Head Stack Assembly (HSA) constituting the HDA appears directly in a position error signal (PES) and prevents a servo-tracking control from being stably performed in the HDD.
In this connection, Korean Patent Laid-open Publication No. 2000-047652 and U.S. Patent Application Publication No. 2002-041472 suggest techniques of detecting and compensating for a resonance frequency occurring in a data storage system. In detail, Korean Patent Laid-open Publication No. 2000-047652 discloses a technique of filtering a resonance frequency, wherein a frequency in a PES obtained using servo information stored in a data storage medium is converted using a Fast Fourier Transformation (FFT), a PES-frequency transformed sample is obtained using a predetermined Goertzel's algorithm, a resonance frequency is calculated using a velocity associated with the particular sample having a maximum magnitude, and the resonance frequency is filtered using a programming filter.
U.S. Patent Application Publication No. 2002-041472 discloses a technique of determining a resonance frequency by detecting a movement of an actuator arm, collecting a data point from a PES regarding the movement, and performing a digital Fourier transformation on the data point.
However, the above prior art techniques allow a resonance frequency to be detected by performing a frequency transformation using a transformation such as the FFT, thus detecting only resonance frequencies within a Nyquist frequency band. That is, it is impossible to detect latent resonance frequencies within a sampling frequency band outside the Nyquist frequency band.